1. Field of the Invention
This invention pertains to polishing of copper on semiconductor devices to a roughness of less than about 6 .ANG. without imparting scratches.
2. Description of Related Art
Copper is a candidate for on-chip interconnections for ultralarge-scale integrated circuits. Chemical mechanical polishing is an important technique in creating a planarized surface for copper laid connections. The current polishing techniques usually use alumina abrasive in either ammonia or nitric acid or hydrogen peroxide based slurries. Due to the softness of copper, this generally creates macro and micro-scratches. These scratches generate problems in quality control and device performance, especially in small featured devices.
Roughness of a copper surface is a critical issue in magnetic devices because soft and hard magnetic layers tend to magnetically couple to each other when they are grown on a rough yet soft copper surface. This coupling is detrimental to the magnetic properties of an electronic magnetic device.
U.S. Pat. No. 5,800,577 to Kido discloses a polishing composition for chemical mechanical polishing of copper comprising a carboxylic acid, an oxidizing agent, and water. The polishing composition is adjusted with an alkali to a pH of 5-9.
The Kido U.S. Pat. No. 5,800,577 discloses in col.2 a polishing composition comprising an etching agent containing an aminoacetic acid and/or an amidosulfonic acid, an oxidizing agent, water and a chemical agent which contains at least benzotriazole or a derivative thereof, which forms a protective layer on a material for circuits.
The Kido U.S. Pat. No. 5,800,577 alleges for its polishing composition high polishing rate and formation of few corrosion marks or dishing resulting in a high precision finished surface which is advantageously used in production of semiconductor devices.